Need to know the best way to support him
It depends on the issue of what happened, most of our DUI cases are defended on procedural defenses of violation with gathering evidence, or Title 17 violations, as well a actual defense to a DUI of not driving or less than the BAC.
Free consult with an attorney about the case would answer this better depending on what happened as well a price quote for the defense costs. Court and DMV have different issue in a DUI case.
without knowing more facts it is hard to say.
however you do not just hire a lawyer to prove your son innocent/not guilty..................................
the biggest consideration is the sentence and a good lawyer can often have a say in the sentence.